Any advise
I always buy head castings bare so I can put in good components. The head manufacturers mostly use import valves and only average quality springs to sell their packages cheaper on the market.
I use Manley Severe Duty stainless valves only.
For Titanium valves I use Victory over Manley in blower applications. Had some valve failures which stopped with the change to Victory. (Heads and tips broke off)
As far as springs I use Manley NEXTEK mostly but PAC is made from KOBE steel which is a cleaner material and is better quality wise compared to Manley steel. PSI is also better than Manley. PAC and PSI are manufacturers and Manley buys theirs from Superior Spring from an Erson design. (Correct me on this if I am off a little.)
Victory sells PAC springs, high quality retainers and keepers. I buy the whole package from them if I use Titanium valves.